If you book a Pre-Cruise hotel package through the cruise line they do provide all the transfers Airport to hotel/hotel to pier/pier back to airport. Generally, their hotel packages are on a per person basis and are usually higher than what you can do on your own. You would need to look at it both ways and compare their package to booking a hotel separate and what transfers may be included by shuttle or if you would need to pay for a taxi. Depending which port you're looking at there may be hotels that offer all the transfers in a cruise package. I would also consider the location of where the hotels are. If they are out by the airport they most likely won't have a lot of things close by for you to walk to. Then you would have to consider taxi cost to go out to eat, etc.